style(button): 优化按钮样式和尺寸

- 添加中等尺寸按钮的样式
- 移除自定义 render-button 类样式
-统一使用 Element UI 的 size="medium" 属性
-调整按钮的其他样式属性，如字体和对齐方式

src/views/knowledge/index.vue

@@ -43,8 +43,8 @@
               {{ item.segmentedMode | filterSegmentedMode }}
             </div>
             <div class="opacity-button">
-              <el-button class="default render-button" icon="el-icon-delete" @click.stop="deleteKnowLedge(item)">删除</el-button>
-              <el-button class="render-button line-button" icon="el-icon-edit" @click.stop="createdKnowLedge(item)" type="primary">修改</el-button>
+              <el-button class="default " size="medium" icon="el-icon-delete" @click.stop="deleteKnowLedge(item)">删除</el-button>
+              <el-button class="line-button" size="medium" icon="el-icon-edit" @click.stop="createdKnowLedge(item)" type="primary">修改</el-button>
             </div>
           </div>